I've noticed that only couple types of wands will ever be bought and used by players. First there are healing items, like wands and scrolls of cure light wounds(caster level 1st). Then there are buff spells, like enlarge person and mage armor. Then there are utility items, like 3.5 knock or command undead, that is useful to have in scroll form in case it's needed.
Then there are the items nobody ever uses. These are things like a scroll of cause fear or a wand of fireball that just cost too much, are easy to save against and even if someone fails their save, the effect suffered is underwhelming at best.
I believe this has to do with two things. The low DC and lousy caster level / cost ratio.
A good solution to this problem should not make often used items more powerful or cheaper, but only reduce the cost of items not likely bought. My own fix would be to tinker with magic item pricing, so that scrolls, potions and wands would have a base price of (X * spell level * minimum caster level needed to cast spell), where X is 25 for scrolls, 50 for potions and 15 for wands. Then, if a crafter wanted to create an item at a higher caster level, he'd have to pay additional sum that's less than what he would pay using the current rules. For example, if each additional caster level above the minimum cost only half (for example, a scroll would cost: base price + 12,5 * spell level * (item's actual caster level - minimum caster level required to create item), a wand of fireball (caster level 10th) would cost 16 875(11 250 for caster level 5 wand plus 5 625 for increase of five caster levels)
This ensures that a wand of fireball (caster level 5th) would not become cheaper, but a wand of fireball (caster level 10th) would.